Doug S replied to the topic 'New Focus Algorithm in Ekos' in the forum. 7 months ago

Hi John, IMHO, the only step size that is "appropriate" is one that is tightly correlated to the CFZ size (in microns) for the instrument. This is what the Critical CFZ discussion I previously posted is all about. It's seeing and focus tolerance dependent after factoring f/ratio and aperture size. Whether one wants to be conservative and use a step size that is 1/2 CFZ (to always be sure to land in it), or less conservative (~1 CFZ) could be a user choice (but with potential consequences).

It would be best if the algorithm calculated step size from user input of how many microns per revolution the focus motor has, and how many microns of focuser drawtube travel occurs per revolution of the focusing mechanism. Not knowing these two values, and just "winging" a generic step size is just guessing. Folks should try to get some understanding of their CFZ and then set a step size to match the instrument. Since some will not want or know this info (or won't want to go to the trouble to find it), the guess may need to be allowed. But a better solution would be to allow for a precise calculation when the parameters are known.

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